Morphological changes of the liver of the rats which had sustained common bile duct ligation for twenty-four to seventy two hours were studied by staining with hematoxylin-eosin and Periodic acid Schiff reaction. Histochemical stainings for enzymatic activity such as acid phosphatase, alkaline phosphatase, 5'-nucleotidase and adenosintriphosphatase were also applied. In other rats, saccharated ferric oxide was injected in the common bile duct at various intervals after common bile duct ligation and then liver sections were stained with iron reaction. Following results were obtained. 1) In the normal liver, canalicular-sinusoidal connections were more numerous in the central area than in the peripheral zone of the lobule. The number of the connections ranged from several to some dozen per 5 micron section of a lodule. 2) The width of canalicular-sinusoidal connections was increased after 24 hours of common bile duct ligation and both the number and width of the connections showed increase after 48 hours of ligation. 3) Under conditions of common bile duct ligation and administration of saccharated ferric oxide by intrabiliary injection, iron reaction-positive granules were found in canalicular-sinusoidal connections as a linear deposit. 4) Main route for the regurgitation of biliary contents at the early stage of obstructive jaundie is presumed to be canalicular-sinusoidal connections.